(1B) The product $(a+b)(c+d)$
Practice
Expand and simplify.
*Write your answers with powers of $x$ in descending order. $\left(\square x^2 \pm \square x \pm \square\right)$
$\left(x+1\right)\left(x-7\right)$
$\left(x-5\right)\left(x-7\right)$
$\left(x+9\right)\left(-8+x\right)$
$\left(x+9\right)\left(8+x\right)$
$\left(-9+x\right)\left(x-8\right)$
$\left(-7+x\right)\left(-x+9\right)$
$\left(3-x\right)\left(-4+x\right)$
$\left(-4+x\right)\left(-3+x\right)$
$\left(x+1\right)\left(-4x+5\right)$
$\left(6x+1\right)\left(4x-5\right)$
$\left(7x+5\right)\left(1-7x\right)$
$\left(3x-7\right)\left(7+x\right)$
$\left(1+x\right)\left(5x-9\right)$
$\left(2-5x\right)\left(8x-5\right)$
$\left(7-3x\right)\left(1-9x\right)$
$\left(7-4x\right)\left(3+5x\right)$